1. Field of the invention
The present invention relates to a novel polymer comprising fluoroalkyl group, a novel method of preparation thereof, a novel surface active agent, a novel surface treatment agent and a novel coating composition.
2. Description of the prior art
Organic compounds comprising fluoroalkyl group in the molecule have been attracting attention because of the advantageous properties such as weatherability, water repellency, oil repellency and physiological activity. Particularly, polymers comprising fluoroalkyl group in which the fluoroalkyl group is chemically introduced into the polymeric molecule have advantageous properties such as low surface tension, low light refractivity, heat resistance, cold resistance, oil resistance, electric insulation, water repellency, mold releasing property, resistance against chemicals and the like and have been considered to be useful for application to the area of surface treatment to provide properties like water repellency, oil repellency and resistance against fouling to surfaces of optical lenses, lenses of spectacles, glass apparatuses, coated layers and the like, to the area of materials for biological applications, medicines and agricultural chemicals and to the area of providing materials with mold releasing property. However, conventional polymers comprising fluoroalkyl group have a problem that weatherability is inferior because the fluoroalkyl group is introduced through ester linkage to acrylic acid or methacrylic acid or through amino linkage. An example of epoxy compound comprising fluoroalkyl group in which the fluoroalkyl group is introduced through amino linkage is described in J. Fluorine Chem. volume 55, page 1 (1991). Acrylic coating materials comprising fluoroalkyl group have problems that the fluoroalkyl group is easily eliminated by hydrolysis and the water repellency and the oil repellency are decreased and that resistance against fouling is insufficient because the fluoroalkyl group is introduced into the polymer through ester linkage. A fluororesin coating material developed for the purpose of improvement of weatherability by using chlorotrifluoroethylene (Yuki Gosei Kagaku Kyokaishi, volume 42, page 841 (1992)) has a problem that the water repellency and the oil repellency are inferior and the resistance against fouling is insufficient even though it has good weatherability.
Fluororesins comprising fluoroalkyl group such as fluoroacrylate polymers comprising fluoroalkyl group introduced through ester linkage have been widely used as surface treatment agents by which surfaces of articles and apparatuses are provided with protected surfaces, beautiful appearance, water repellency, oil repellency, electric insulation, mold releasing property, resistance against fouling and the like through the coating layer formed on the surface. However, the fluororesins have problems that they have inferior adhesive property to inorganic materials such as metals, glasses, cement and the like and organic materials such as various kind of plastics, substrates and the like and that they have inferior stability against acids and alkalis because the fluoroalkyl group is introduced into the polymer molecule through ester linkage.
For the purpose of improving the problems described above, silicone compounds comprising fluoroalkyl group were proposed in literatures such as Laid Open Japanese Patent Application Showa 59-10280. However, the silicone compounds cannot improve the adhesive property to the satisfactory degree and has an additional problem that the water repellency and the oil repellency are decreased.
Recently, it is considered that surface active agents and surface treatment agents comprising fluoroalkyl group having the water repellency and the oil repellency and amphiphillic group having hydrophillic property in the same molecule will be useful as SR processing agents, antifogging agents, surface active agents and surface treatment agents and the development of such kind of agents is urgently desired.
Thus, development of agents comprising fluoroalkyl group introduced directly through carbon-carbon linkage in the molecule and having excellent water repellency and the oil repellency is urgently desired.